ACPI: processor: Fix previous acpi_processor_errata_piix4() fix

After commi f132e089fe89 ("ACPI: processor: Fix NULL-pointer dereference
in acpi_processor_errata_piix4()"), device pointers may be dereferenced
after dropping references to the device objects pointed to by them,
which may cause a use-after-free to occur.

Moreover, debug messages about enabling the errata may be printed
if the errata flags corresponding to them are unset.

Address all of these issues by moving message printing to the points
in the code where the errata flags are set.

Fixes: f132e089fe89 ("ACPI: processor: Fix NULL-pointer dereference in acpi_processor_errata_piix4()")
Reported-by: Guenter Roeck <linux@roeck-us.net>
Closes: https://lore.kernel.org/linux-acpi/938e2206-def5-4b7a-9b2c-d1fd37681d8a@roeck-us.net/
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Link: https://patch.msgid.link/5975693.DvuYhMxLoT@rafael.j.wysocki

diff --git a/drivers/acpi/acpi_processor.c b/drivers/acpi/acpi_processor.c
index b34a48068a8d125d29c2c61a490670ab94c3bc68..b1652cab631aa34980744c373fa956342c6d9855 100644 (file)
--- a/drivers/acpi/acpi_processor.c
+++ b/drivers/acpi/acpi_processor.c
@@ -113,6 +113,10 @@ static int acpi_processor_errata_piix4(struct pci_dev *dev)
                                     PCI_ANY_ID, PCI_ANY_ID, NULL);
                if (ide_dev) {
                        errata.piix4.bmisx = pci_resource_start(ide_dev, 4);
+                       if (errata.piix4.bmisx)
+                               dev_dbg(&ide_dev->dev,
+                                       "Bus master activity detection (BM-IDE) erratum enabled\n");
+
                        pci_dev_put(ide_dev);
                }
 
@@ -131,20 +135,17 @@ static int acpi_processor_errata_piix4(struct pci_dev *dev)
                if (isa_dev) {
                        pci_read_config_byte(isa_dev, 0x76, &value1);
                        pci_read_config_byte(isa_dev, 0x77, &value2);
-                       if ((value1 & 0x80) || (value2 & 0x80))
+                       if ((value1 & 0x80) || (value2 & 0x80)) {
                                errata.piix4.fdma = 1;
+                               dev_dbg(&isa_dev->dev,
+                                       "Type-F DMA livelock erratum (C3 disabled)\n");
+                       }
                        pci_dev_put(isa_dev);
                }
 
                break;
        }
 
-       if (ide_dev)
-               dev_dbg(&ide_dev->dev, "Bus master activity detection (BM-IDE) erratum enabled\n");
-
-       if (isa_dev)
-               dev_dbg(&isa_dev->dev, "Type-F DMA livelock erratum (C3 disabled)\n");
-
        return 0;
 }